This invention relates to a solenoid valve, in particular for hydraulic brake systems with slip control.
There are many practical applications for such conventional, well-known valves for controlling the flow of fluids in slip-controlled hydraulic brake systems.
German Patent Application No. P 37 01 019.0 discloses a solenoid valve for a slip-controlled hydraulic brake system consisting of a valve seat which receives a valve tappet excitable by a solenoid and guided in an axially movable manner within a valve housing and having an annular flow cross-section controllably arranged between the valve tappet and the valve seat and communicating with the pressure medium channels which project into the valve housing. In order to control all the brake circuits, several valves are combined advantageously in a valve block housing, so that a space-saving positioning of all solenoid valves is ensured in an economical, low-cost manner.
A shortcoming of this known valve design is its noise behavior during the operating phases of the valve which is caused by the non-uniform flow behavior and, hence, by the discontinuous flow bypassing the valve closure member because of the binary valve operating positions.
In order to reduce the development of noise and, hence, the transmission of sounds, at present, considerable passive, as well as active, noise dampening efforts have been tried. However, all such known efforts have involved considerable cost and the results have required optimizing.